Fig. 2 shows the colour parameters of the kernels and
flours from rice with different DOM. Brightness (L*) of
the raw rice kernels and the rice flours increased until a
DOM of ca. 15% (bran and outer endosperm removed)
(Fig. 2A). Further milling did not affect the rice brightness.
For the raw rice kernels and rice flours, redness (a*) and
yellowness (b*) decreased until a DOM of ca. 15% was
reached (Fig. 2B and C). This indicated that the levels of
red and yellow pigments decreased from the surface of
the brown rice to the middle endosperm. It also demonstrated
that bran and outer endosperm contain more red
and yellow pigments than the middle and core endosperm.
It seems that the pigments are uniformly distributed in the
middle and core endosperm. Furthermore, these endosperm
fractions contained very low levels of red pigments
since a* is approximately 0. The differences between the colour
parameters of the flour from rice with different DOM
were smaller than the differences between the colour
parameters of the rice kernels themselves. This may be
explained by a dilution effect. Grinding of rice kernels
results in a mix of a small dark, coloured fraction (bran
and outer endosperm) and a large light, less pigmented
fraction (middle and core endosperm).